https://en.wikipedia.org/wiki/Phenomenalism
Phenomenalism is the view that physical objects cannot justifiably be said to exist in themselves, but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in time and in space. In particular, some forms of phenomenalism reduce talk about physical objects in the external world to talk about bundles of sense-data.
Phenomenalism is the view that physical objects cannot justifiably be said to exist in themselves, but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in time and in space. In particular, some forms of phenomenalism reduce talk about physical objects in the external world to talk about bundles of sense-data.
History
Phenomenalism is a radical form of empiricism. Its roots as an ontological view of the nature of existence can be traced back to George Berkeley and his subjective idealism, upon which David Hume further elaborated. John Stuart Mill
had a theory of perception which is commonly referred to as classical
phenomenalism. This differs from Berkeley's idealism in its account of
how objects continue to exist when no one is perceiving them (this view
is also known as "local realism").
Berkeley claimed that an omniscient God perceived all objects and that
this was what kept them in existence, whereas Mill claimed that
permanent possibilities of experience were sufficient for an object's
existence. These permanent possibilities could be analysed into counterfactual conditionals, such as "if I were to have y-type sensations, then I would also have x-type sensations".
As an epistemological
theory about the possibility of knowledge of objects in the external
world, however, it is probable that the most easily understandable
formulation of phenomenalism is to be found in the transcendental aesthetics of Immanuel Kant. According to Kant, space and time, which are the a priori
forms and preconditions of all sensory experience, "refer to objects
only to the extent that these are considered as phenomena, but do not
represent the things in themselves". While Kant insisted that knowledge
is limited to phenomena,
he never denied or excluded the existence of objects which were not
knowable by way of experience, the things-in-themselves or noumena, though he never proved them.
Kant's "epistemological phenomenalism", as it has been called, is
therefore quite distinct from Berkeley's earlier ontological version.
In Berkeley's view, the so-called "things-in-themselves" do not exist
except as subjectively perceived bundles of sensations which are
guaranteed consistency and permanence because they are constantly
perceived by the mind of God. Hence, while Berkeley holds that objects are merely bundles of sensations (see bundle theory),
Kant holds (unlike other bundle theorists) that objects do not cease to
exist when they are no longer perceived by some merely human subject or mind.
In the late 19th century, an even more extreme form of phenomenalism was formulated by Ernst Mach, later developed and refined by Russell, Ayer and the logical positivists. Mach rejected the existence of God
and also denied that phenomena were data experienced by the mind or
consciousness of subjects. Instead, Mach held sensory phenomena to be
"pure data" whose existence was to be considered anterior to any
arbitrary distinction between mental and physical categories of
phenomena. In this way, it was Mach who formulated the key thesis of
phenomenalism, which separates it from bundle theories of objects:
objects are logical constructions out of sense-data or ideas; whereas according to bundle theories, objects are made up of sets, or bundles, of actual ideas or perceptions.
That is, according to bundle theory, to say that the pear before
me exists is simply to say that certain properties (greenness, hardness,
etc.) are being perceived at this moment. When these characteristics
are no longer perceived or experienced by anyone, then the object (pear,
in this case) no longer exists. Phenomenalism as formulated by Mach, in
contrast, is the view that objects are logical constructions out
of perceptual properties. On this view, to say there is a table in the
other room when there is no one in that room to perceive it, is to say
that if there were someone in that room, then that person would perceive the table. It is not the actual perception that counts, but the conditional possibility of perceiving.
Logical positivism, a movement begun as a small circle which grew around the philosopher Moritz Schlick
in Vienna, inspired many philosophers in the English speaking world
from the 1930s through the 1950s. Important influences on their brand of
empiricism included Ernst Mach — himself holding the Chair of Inductive
Sciences at the University of Vienna, a position Schlick would later
hold — and the Cambridge philosopher Bertrand Russell. The idea of the logical positivists, such as A.J. Ayer and Rudolf Carnap,
was to formulate the doctrine of phenomenalism in linguistic terms, so
as to define out of existence references to such entities as physical
objects in the external world. Sentences which contained terms such as
"table" were to be translated into sentences which referred exclusively
to either actual or possible sensory experiences.
20th century American philosopher Arthur Danto
asserted that "a phenomenalist, believ[es] that whatever is finally
meaningful can be expressed in terms of our own [sense] experience.".
He claimed that "The phenomenalist really is committed to the most
radical kind of empiricism: For him reference to objects is always
finally a reference to sense-experience ... ."
To the phenomenalist, objects of any kind must be related to experience. "John Stuart Mill
once spoke of physical objects as but the 'permanent possibility of
experience' and this, by and large, is what the phenomenalist exploits:
All we can mean, in talking about physical objects — or nonphysical
objects, if there are any — is what experiences we would have in dealing
with them ... ." However, phenomenalism is based on mental operations.
These operations, themselves, are not known from sense experience. Such
non-empirical, non-sensual operations are the "...nonempirical matters
of space, time, and continuity that empiricism in all its forms and
despite its structures seems to require ... ."
See for comparison Sensualism, to which phenomenalism is closely related.
Criticisms
Roderick Chisholm criticized the logical positivist version of phenomenalism in 1948. C.I. Lewis had previously suggested that the physical claim "There is a doorknob in front of me" necessarily entails
the sensory conditional "If I should seem to see a doorknob and if I
should seem to myself to be initiating a grasping motion, then in all
probability the sensation of contacting a doorknob should follow".
Chisholm objected that the statement "There is a doorknob..." does not
entail the counterfactual statement, for if it were to do so, then it
must do so without regard to the truth or falsity of any other
statement; but suppose the following statement was true: "I am paralyzed
from the neck down and experience hallucinations such that I seem to
see myself moving toward the door". If this were true, Chisholm
objected, then there could be a doorknob in front of me, I could seem to
myself to see a doorknob, and I could seem to myself to be performing
the correct sort of grasping motion, but with absolutely no chance of
having a sensation of contacting the doorknob. Likewise, he objected
that the statement that "The only book in front of me is red" does not
entail the sensory statement "Redness would probably appear to me were I
to seem to myself to see a book", because redness is not likely to
appear under a blue light-bulb. Some
have tried to avoid this problem by extending the conditions in the
analysandum: instead of "There is a doorknob in front of me" one could
have it that "There is a doorknob, and I am not paralyzed, etc." In
response, Chisholm objects that if one complicates the analysandum, one
must also complicate the analysans; in this particular case, that one
must analyse in purely sensory terms what it means not to be paralyzed
and so on, with respect to which the same problems would arise leading
to an infinite regress.
Another common
objection to phenomenalism is that in the process of eliminating
material objects from language and replacing them with hypothetical
propositions about observers and experiences, it seems to commit us to
the existence of a new class of ontological object altogether: the sensibilia or sense-data which can exist independently of experience. Indeed, sense-data have been dismissed by some philosophers of mind, such as Donald Davidson, as mythological entities that are more troublesome than the entities that they were intended to replace.
A third common objection in the literature
is that phenomenalism, in attempting to convert propositions about
material objects into hypothetical propositions about sensibilia,
postulates the existence of an irreducibly material observer in the
antecedent of the conditional. In attempting to overcome this, some
phenomenalists
suggested that the first observer could be reduced by constructing a
second proposition in terms of a second observer, who actually or
potentially observes the body of the first observer. A third observer
would observe the second and so on. In this manner we would end up with a
"Chinese box
series of propositions" of ever decreasing material content ascribed to
the original observer. But if the final result is not the complete elimination
of the materiality of the first observer, then the translational
reductions that are proposed by phenomenalists cannot, even in
principle, be carried out.
Another criticism is that the phenomenalist can give no
satisfactory explanation of the permanent possibilities of experience.
The question can be asked, "What are the counterfactual conditionals which ground the existence of objects true
in virtue of?" One answer given by phenomenalists is that the
conditionals are true in virtue of past regularities of experience.
However, critics object that this answer leads to circularity: first our actual experience was meant to be explained by the possibility of experience, and now the possibility of experience is meant to be explained by our actual past experience. A further objection to the phenomenalist answer is that generally speaking, conditionals
are not true in virtue of their past occurrences. This is because it
seems that a conditional could be true even if it never actually
obtained, and also past occurrences only confirm that a conditional is true, but never make it so.
Roderick Firth
formulated another objection in 1950, stemming from perceptual
relativity: White wallpaper looks white under white light and red under
red light, etc. Any possible course of experience resulting from a
possible course of action will apparently underdetermine our
surroundings: it would determine, for example, that there is either white wallpaper under red light or
red wallpaper under white light, and so on. On what basis are we to
decide which of the hypotheses is the correct one if we are constrained
to rely exclusively on sensibilia?
Notable proponents
- Johannes Nikolaus Tetens
- John Foster (phenomenalistic idealist)
